boolean bRedColor = true;
  
if(bRedColor){
  //paint the rectangle with a red color
  stroke(255,0,0);
  fill(255,0,0);
}
else{
  //paint the rectangle with a green color
  stroke(0,255,0);
  fill(0, 255, 0);
}
 
//draw a rectangle.
rect(0, 0, 100, 80); 



